The present invention relates to improvements in plastic reclosable fasteners or zippers with sliders for opening and closing the zippers on plastic-film bags and the like and particularly to the provision of plastic end stops at the ends of the plastic zipper to seal the ends of the zipper and to provide stops to retain the slider on the zipper.
Plastic reclosable fasteners or zippers with sliders are well known in the art. The plastic zippers include a pair of male and female fastener elements in the form of reclosable interlocking rib and groove profile elements for cooperation with a slider for opening and closing the rib and groove elements. In the manufacture of plastic-film bags, a pair of these male and female plastic profile elements extend along the mouth of the bag and are secured in any suitable manner to the flexible walls of the plastic-film bag. These zipper elements may be integral marginal portions of such walls or they may be extruded separately and thereafter attached to the walls along the mouth of the bag.
Various arrangements have been utilized heretofore to prevent the slider from sliding off either end of the zipper. In one of the more conventional arrangements, the slider includes a separator finger that extends down between the integral locking rib and groove elements as the slider is moved from one edge of the bag to the other edge of the bag. When this bag is opened, the slider is stopped by the side seam at the edge of the bag as the separator finger comes into contact with it. This prior art is described in Herz U.S. Pat. No. 3,790,992. In that patent there is disclosed an arrangement wherein the heat seals that join the rib and groove elements are made wider at one edge than at the second edge of the bag and the wider seal is of a width at least equal to the length of the slider from its closing end to the separator finger so that the slider remains fully on the bag at the end of its travel when the bag is opened. The patent states that these seal areas provide stops for the slider. A second arrangement for providing stops for a slider at the ends of the zipper is disclosed in Zimmerman U.S. Pat. No. 3,259,951. In this patent, opposing interlocking or mating strips are permanently joined or sealed to each other at the ends with a separate stop member sealed between these members to stop the longitudinal movement of the slider therealong. Another arrangement is described in Herrington U.S. Pat. No. 5,088,971 and in Herrington et al U.S. Pat. No. 5,131,121 which disclose end stops that are created from existing material of the profile rib and groove elements at the opposite ends of the reclosable fastener, and that protrude transversely from the fastener a distance adequate to engage the sides of the slider and thus prevent movement of the slider past the respective ends of the bag. With this arrangement, the size of the end stops is limited by the volume of material available in the ends of the rib and groove elements. Another prior art arrangement is described in Herrington et al U.S. Pat. No. 5,161,286. In this patent end clamp members are located at the opposite ends of the reclosable fastener. A pair of end clamp members is connected together by a flexible strap which extends over the top of the zipper and by a rivet that extends through the pair of end clamp members and the sidewalls of the bag below the profile rib and groove elements of the zipper to secure the end clamp members to the bag.
It would be desirable to provide plastic bags with zipper closures wherein the zipper is terminated by the addition of plastic end stops which are bonded to the zipper and thus create a stronger seal. The use of such tubular end stops also provides for ease in assembly of the end stops with the zipper.